/*

This file is part of Ext JS 4

Copyright (c) 2011 Sencha Inc

Contact:  http://www.sencha.com/contact

Commercial Usage
Licensees holding valid commercial licenses may use this file in accordance with the Commercial Software License Agreement provided with the Software or, alternatively, in accordance with the terms contained in a written agreement between you and Sencha.

If you are unsure which license is appropriate for your use, please contact the sales department at http://www.sencha.com/contact.

*/
/**
 * @class Ext.selection.Model
 * @extends Ext.util.Observable
 *
 * Tracks what records are currently selected in a databound widget.
 *
 * This is an abstract class and is not meant to be directly used.
 *
 * DataBound UI widgets such as GridPanel, TreePanel, and ListView
 * should subclass AbstractStoreSelectionModel and provide a way
 * to binding to the component.
 *
 * The abstract methods onSelectChange and onLastFocusChanged should
 * be implemented in these subclasses to update the UI widget.
 */
Ext.define('Ext.selection.Model', {
    extend: 'Ext.util.Observable',
    alternateClassName: 'Ext.AbstractSelectionModel',
    requires: ['Ext.data.StoreManager'],
    // lastSelected

    /**
     * @cfg {String} mode
     * Modes of selection.
     * Valid values are SINGLE, SIMPLE, and MULTI. Defaults to 'SINGLE'
     */

    /**
     * @cfg {Boolean} allowDeselect
     * Allow users to deselect a record in a DataView, List or Grid. Only applicable when the SelectionModel's mode is 'SINGLE'. Defaults to false.
     */
    allowDeselect: false,

    /**
     * @property selected
     * READ-ONLY A MixedCollection that maintains all of the currently selected
     * records.
     */
    selected: null,


    /**
     * Prune records when they are removed from the store from the selection.
     * This is a private flag. For an example of its usage, take a look at
     * Ext.selection.TreeModel.
     * @private
     */
    pruneRemoved: true,

    constructor: function(cfg) {
        var me = this;

        cfg = cfg || {};
        Ext.apply(me, cfg);

        me.addEvents(
            /**
             * @event selectionchange
             * Fired after a selection change has occurred
             * @param {Ext.selection.Model} this
             * @param  {Array} selected The selected records
             */
             'selectionchange'
        );

        me.modes = {
            SINGLE: true,
            SIMPLE: true,
            MULTI: true
        };

        // sets this.selectionMode
        me.setSelectionMode(cfg.mode || me.mode);

        // maintains the currently selected records.
        me.selected = Ext.create('Ext.util.MixedCollection');

        me.callParent(arguments);
    },

    // binds the store to the selModel.
    bind : function(store, initial){
        var me = this;

        if(!initial && me.store){
            if(store !== me.store && me.store.autoDestroy){
                me.store.destroy();
            }else{
                me.store.un("add", me.onStoreAdd, me);
                me.store.un("clear", me.onStoreClear, me);
                me.store.un("remove", me.onStoreRemove, me);
                me.store.un("update", me.onStoreUpdate, me);
            }
        }
        if(store){
            store = Ext.data.StoreManager.lookup(store);
            store.on({
                add: me.onStoreAdd,
                clear: me.onStoreClear,
                remove: me.onStoreRemove,
                update: me.onStoreUpdate,
                scope: me
            });
        }
        me.store = store;
        if(store && !initial) {
            me.refresh();
        }
    },

    /**
     * Select all records in the view.
     * @param {Boolean} suppressEvent True to suppress any selects event
     */
    selectAll: function(suppressEvent) {
        var me = this,
            selections = me.store.getRange(),
            i = 0,
            len = selections.length,
            start = me.getSelection().length;

        me.bulkChange = true;
        for (; i < len; i++) {
            me.doSelect(selections[i], true, suppressEvent);
        }
        delete me.bulkChange;
        // fire selection change only if the number of selections differs
        me.maybeFireSelectionChange(me.getSelection().length !== start);
    },

    /**
     * Deselect all records in the view.
     * @param {Boolean} suppressEvent True to suppress any deselect events
     */
    deselectAll: function(suppressEvent) {
        var me = this,
            selections = me.getSelection(),
            i = 0,
            len = selections.length,
            start = me.getSelection().length;

        me.bulkChange = true;
        for (; i < len; i++) {
            me.doDeselect(selections[i], suppressEvent);
        }
        delete me.bulkChange;
        // fire selection change only if the number of selections differs
        me.maybeFireSelectionChange(me.getSelection().length !== start);
    },

    // Provides differentiation of logic between MULTI, SIMPLE and SINGLE
    // selection modes. Requires that an event be passed so that we can know
    // if user held ctrl or shift.
    selectWithEvent: function(record, e, keepExisting) {
        var me = this;

        switch (me.selectionMode) {
            case 'MULTI':
                if (e.ctrlKey && me.isSelected(record)) {
                    me.doDeselect(record, false);
                } else if (e.shiftKey && me.lastFocused) {
                    me.selectRange(me.lastFocused, record, e.ctrlKey);
                } else if (e.ctrlKey) {
                    me.doSelect(record, true, false);
                } else if (me.isSelected(record) && !e.shiftKey && !e.ctrlKey && me.selected.getCount() > 1) {
                    me.doSelect(record, keepExisting, false);
                } else {
                    me.doSelect(record, false);
                }
                break;
            case 'SIMPLE':
                if (me.isSelected(record)) {
                    me.doDeselect(record);
                } else {
                    me.doSelect(record, true);
                }
                break;
            case 'SINGLE':
                // if allowDeselect is on and this record isSelected, deselect it
                if (me.allowDeselect && me.isSelected(record)) {
                    me.doDeselect(record);
                // select the record and do NOT maintain existing selections
                } else {
                    me.doSelect(record, false);
                }
                break;
        }
    },

    /**
     * Selects a range of rows if the selection model {@link #isLocked is not locked}.
     * All rows in between startRow and endRow are also selected.
     * @param {Ext.data.Model/Number} startRow The record or index of the first row in the range
     * @param {Ext.data.Model/Number} endRow The record or index of the last row in the range
     * @param {Boolean} keepExisting (optional) True to retain existing selections
     */
    selectRange : function(startRow, endRow, keepExisting, dir){
        var me = this,
            store = me.store,
            selectedCount = 0,
            i,
            tmp,
            dontDeselect,
            records = [];

        if (me.isLocked()){
            return;
        }

        if (!keepExisting) {
            me.deselectAll(true);
        }

        if (!Ext.isNumber(startRow)) {
            startRow = store.indexOf(startRow);
        }
        if (!Ext.isNumber(endRow)) {
            endRow = store.indexOf(endRow);
        }

        // swap values
        if (startRow > endRow){
            tmp = endRow;
            endRow = startRow;
            startRow = tmp;
        }

        for (i = startRow; i <= endRow; i++) {
            if (me.isSelected(store.getAt(i))) {
                selectedCount++;
            }
        }

        if (!dir) {
            dontDeselect = -1;
        } else {
            dontDeselect = (dir == 'up') ? startRow : endRow;
        }

        for (i = startRow; i <= endRow; i++){
            if (selectedCount == (endRow - startRow + 1)) {
                if (i != dontDeselect) {
                    me.doDeselect(i, true);
                }
            } else {
                records.push(store.getAt(i));
            }
        }
        me.doMultiSelect(records, true);
    },

    /**
     * Selects a record instance by record instance or index.
     * @param {Ext.data.Model/Index} records An array of records or an index
     * @param {Boolean} keepExisting
     * @param {Boolean} suppressEvent Set to false to not fire a select event
     */
    select: function(records, keepExisting, suppressEvent) {
        this.doSelect(records, keepExisting, suppressEvent);
    },

    /**
     * Deselects a record instance by record instance or index.
     * @param {Ext.data.Model/Index} records An array of records or an index
     * @param {Boolean} suppressEvent Set to false to not fire a deselect event
     */
    deselect: function(records, suppressEvent) {
        this.doDeselect(records, suppressEvent);
    },

    doSelect: function(records, keepExisting, suppressEvent) {
        var me = this,
            record;

        if (me.locked) {
            return;
        }
        if (typeof records === "number") {
            records = [me.store.getAt(records)];
        }
        if (me.selectionMode == "SINGLE" && records) {
            record = records.length ? records[0] : records;
            me.doSingleSelect(record, suppressEvent);
        } else {
            me.doMultiSelect(records, keepExisting, suppressEvent);
        }
    },

    doMultiSelect: function(records, keepExisting, suppressEvent) {
        var me = this,
            selected = me.selected,
            change = false,
            i = 0,
            len, record;

        if (me.locked) {
            return;
        }


        records = !Ext.isArray(records) ? [records] : records;
        len = records.length;
        if (!keepExisting && selected.getCount() > 0) {
            if (me.doDeselect(me.getSelection(), suppressEvent) === false) {
                return;
            }
            // TODO - coalesce the selectionchange event in deselect w/the one below...
        }

        function commit () {
            selected.add(record);
            change = true;
        }

        for (; i < len; i++) {
            record = records[i];
            if (keepExisting && me.isSelected(record)) {
                continue;
            }
            me.lastSelected = record;

            me.onSelectChange(record, true, suppressEvent, commit);
        }
        me.setLastFocused(record, suppressEvent);
        // fire selchange if there was a change and there is no suppressEvent flag
        me.maybeFireSelectionChange(change && !suppressEvent);
    },

    // records can be an index, a record or an array of records
    doDeselect: function(records, suppressEvent) {
        var me = this,
            selected = me.selected,
            i = 0,
            len, record,
            attempted = 0,
            accepted = 0;

        if (me.locked) {
            return false;
        }

        if (typeof records === "number") {
            records = [me.store.getAt(records)];
        } else if (!Ext.isArray(records)) {
            records = [records];
        }

        function commit () {
            ++accepted;
            selected.remove(record);
        }

        len = records.length;
        
        for (; i < len; i++) {
            record = records[i];
            if (me.isSelected(record)) {
                if (me.lastSelected == record) {
                    me.lastSelected = selected.last();
                }
                ++attempted;
                me.onSelectChange(record, false, suppressEvent, commit);
            }
        }

        // fire selchange if there was a change and there is no suppressEvent flag
        me.maybeFireSelectionChange(accepted > 0 && !suppressEvent);
        return accepted === attempted;
    },

    doSingleSelect: function(record, suppressEvent) {
        var me = this,
            changed = false,
            selected = me.selected;

        if (me.locked) {
            return;
        }
        // already selected.
        // should we also check beforeselect?
        if (me.isSelected(record)) {
            return;
        }

        function commit () {
            me.bulkChange = true;
            if (selected.getCount() > 0 && me.doDeselect(me.lastSelected, suppressEvent) === false) {
                delete me.bulkChange;
                return false;
            }
            delete me.bulkChange;

            selected.add(record);
            me.lastSelected = record;
            changed = true;
        }

        me.onSelectChange(record, true, suppressEvent, commit);

        if (changed) {
            if (!suppressEvent) {
                me.setLastFocused(record);
            }
            me.maybeFireSelectionChange(!suppressEvent);
        }
    },

    /**
     * @param {Ext.data.Model} record
     * Set a record as the last focused record. This does NOT mean
     * that the record has been selected.
     */
    setLastFocused: function(record, supressFocus) {
        var me = this,
            recordBeforeLast = me.lastFocused;
        me.lastFocused = record;
        me.onLastFocusChanged(recordBeforeLast, record, supressFocus);
    },

    /**
     * Determines if this record is currently focused.
     * @param Ext.data.Record record
     */
    isFocused: function(record) {
        return record === this.getLastFocused();
    },


    // fire selection change as long as true is not passed
    // into maybeFireSelectionChange
    maybeFireSelectionChange: function(fireEvent) {
        var me = this;
        if (fireEvent && !me.bulkChange) {
            me.fireEvent('selectionchange', me, me.getSelection());
        }
    },

    /**
     * Returns the last selected record.
     */
    getLastSelected: function() {
        return this.lastSelected;
    },

    getLastFocused: function() {
        return this.lastFocused;
    },

    /**
     * Returns an array of the currently selected records.
     * @return {Array} The selected records
     */
    getSelection: function() {
        return this.selected.getRange();
    },

    /**
     * Returns the current selectionMode. SINGLE, MULTI or SIMPLE.
     * @return {String} The selectionMode
     */
    getSelectionMode: function() {
        return this.selectionMode;
    },

    /**
     * Sets the current selectionMode. SINGLE, MULTI or SIMPLE.
     */
    setSelectionMode: function(selMode) {
        selMode = selMode ? selMode.toUpperCase() : 'SINGLE';
        // set to mode specified unless it doesnt exist, in that case
        // use single.
        this.selectionMode = this.modes[selMode] ? selMode : 'SINGLE';
    },

    /**
     * Returns true if the selections are locked.
     * @return {Boolean}
     */
    isLocked: function() {
        return this.locked;
    },

    /**
     * Locks the current selection and disables any changes from
     * happening to the selection.
     * @param {Boolean} locked
     */
    setLocked: function(locked) {
        this.locked = !!locked;
    },

    /**
     * Returns <tt>true</tt> if the specified row is selected.
     * @param {Record/Number} record The record or index of the record to check
     * @return {Boolean}
     */
    isSelected: function(record) {
        record = Ext.isNumber(record) ? this.store.getAt(record) : record;
        return this.selected.indexOf(record) !== -1;
    },

    /**
     * Returns true if there are any a selected records.
     * @return {Boolean}
     */
    hasSelection: function() {
        return this.selected.getCount() > 0;
    },

    refresh: function() {
        var me = this,
            toBeSelected = [],
            oldSelections = me.getSelection(),
            len = oldSelections.length,
            selection,
            change,
            i = 0,
            lastFocused = this.getLastFocused();

        // check to make sure that there are no records
        // missing after the refresh was triggered, prune
        // them from what is to be selected if so
        for (; i < len; i++) {
            selection = oldSelections[i];
            if (!this.pruneRemoved || me.store.indexOf(selection) !== -1) {
                toBeSelected.push(selection);
            }
        }

        // there was a change from the old selected and
        // the new selection
        if (me.selected.getCount() != toBeSelected.length) {
            change = true;
        }

        me.clearSelections();

        if (me.store.indexOf(lastFocused) !== -1) {
            // restore the last focus but supress restoring focus
            this.setLastFocused(lastFocused, true);
        }

        if (toBeSelected.length) {
            // perform the selection again
            me.doSelect(toBeSelected, false, true);
        }

        me.maybeFireSelectionChange(change);
    },

    /**
     * A fast reset of the selections without firing events, updating the ui, etc.
     * For private usage only.
     * @private
     */
    clearSelections: function() {
        // reset the entire selection to nothing
        this.selected.clear();
        this.lastSelected = null;
        this.setLastFocused(null);
    },

    // when a record is added to a store
    onStoreAdd: function() {

    },

    // when a store is cleared remove all selections
    // (if there were any)
    onStoreClear: function() {
        if (this.selected.getCount > 0) {
            this.clearSelections();
            this.maybeFireSelectionChange(true);
        }
    },

    // prune records from the SelectionModel if
    // they were selected at the time they were
    // removed.
    onStoreRemove: function(store, record) {
        var me = this,
            selected = me.selected;

        if (me.locked || !me.pruneRemoved) {
            return;
        }

        if (selected.remove(record)) {
            if (me.lastSelected == record) {
                me.lastSelected = null;
            }
            if (me.getLastFocused() == record) {
                me.setLastFocused(null);
            }
            me.maybeFireSelectionChange(true);
        }
    },

    /**
     * Gets the count of selected records.
     * @return {Number} The number of selected records
     */
    getCount: function() {
        return this.selected.getCount();
    },

    // cleanup.
    destroy: function() {

    },

    // if records are updated
    onStoreUpdate: function() {

    },

    // @abstract
    onSelectChange: function(record, isSelected, suppressEvent) {

    },

    // @abstract
    onLastFocusChanged: function(oldFocused, newFocused) {

    },

    // @abstract
    onEditorKey: function(field, e) {

    },

    // @abstract
    bindComponent: function(cmp) {

    }
});
